Electrical musical instrument



1940- v. H. SEVERY 2,137

ELECTRICAL MUSICAL INSTRUMENT Filad July 13, 1936 4 Sheets-Shoot 1 Jan. 16, 1940. v, H, V RY 2,187,251

ELECTRICAL IE IS'IC AL, INSTRUMENT Filed July 1:5, 19:56 4 Sheets-Sheet 2 R Q m Q & I 2

-v; H. SEVERY ELECTRICAL IUS'ICAL INSTRUMENT Filed July 13, 1936 4 Sheets-Sheet 3 l ZCTOFLH Jlzrrnr Jan. 1

. M V. m

Jln'16,1940- v. H. SEVERYY 2,187,251

ELECTRICAL MUSICAL INSTRUMENT Filed July 13, 1936 4 Sheets-Shoot 4 /40 WCWH 654 2717) mama Jul. 1c, 1940 a 2,187,251 v UNITED STATES PATENT OFFICE vifffsfi'fifmfiffw Application July 13, 1936, Serial No. 90,278

2 Claims. (Cl. 84-1) This invention relates to musical instruments points to be free to vibrate in their characterand relates more particularly to musical instruistic manners.

ments embodying electrostatic pick-ups respon-' A further object of this invention is to prosive to or receptive to the vibration of vibratile vide an electrical musical instrument of the sounders such as bars, i'orks, or the like. A gencharacter mentioned embodying means for goveral object of the invention is to provide a pracerning the intensity of the musical tones and tical efiective electrostatic musical instrument of for independently governing the intensity of the the character just mentioned capable of protremolo effect. ducing clear, pleasing. true musical tones. The various objects and feat r s of my inlo Another object of this invention is to provide vention will be fully understood ilrom the 101- 0 a musical instrument embodying a multiplicity lowing detailed description of typical preferred 'ci' tuned vibratile sounders each capable of flucforms and applications 01' my invention, throughtuating or varying the potential of its respective out which description reference is made to the electrostatic pick-up, which variations in potenaccompanying drawings, in which:

1 tial are in turn imposed on aloud speaker circuit Fig. 1 .is a front elevation of a case or cabinet whereby the vibrations of the individual sounders in wh ch t instrument y be housed- 2 are electrically converted into sound. is a wiring diagram and fragmentary schematic Another object or this invention is to provide view illustrating the electrical circuits and their an electrostatic musical instrument of the charrelationship to the other parts. Fig. 3 is an enacter mentioned in which the vibrators or soundlarged vertical detailed sectional view of the ers are arranged in a compact relation and are strum t l us in K- 2 illustrating One acoustically insulated one from the other so that 01 the sounders, the'adieeen D D d t e there is little or no interference of vibration or e s for Vibrating the de 4 S a transference of vibration from one sounder to the fragmentary top or plan view of a group of the other. sounders and their pick-ups. Fig. 5 is an en- Another object or this invention is to provide ged fragm ta y Vertical detailed Sectional an electrical musical instrument of the character w illustrating O Of the Sounders and its mentioned embodying simple, efl'ective means for D k- 1D- l 6 15 an enlarged Ve tica detailed producing a tremolo eilect. sectional view of the variable condenser for pro- Another object 01' this invention is to provide uc the tremolo ct. Fig. 7 is a perspective an improved electrical musical instrument of the V w O a group 01 Sounders Of a fl e t Che-rcharacter mentioned that may be played and acter and heir oc a p kp Fi 8 is a manipulated in the same manner as a. typical fragmentary side elevation illustrating another musical instrument such asapiano, organ, or the f m 01 Sounder and p With a po t on like. broken away to appear in vertical cross section.

Another object of this invention is to provide Fig. 9 S a fragmentary Perspective V ew 01 Still an electrical musical instrument of the character another form of ounder. Fig. 10 is a fra mentioned embodying a novel relationship bemental-y perspective view of a sounder illustrattween the vibratile sounders and the electrostatic ing an improved manner Supporting the same.

0 pick-ups whereby the vibrations of the sounders 11 15 a P pect elevation V w Of another are properly and fully imposed on picbups form of vibratile sounder. Fig. 12 is a plan view t t danger of direct physical ng of a set or series of bar sounders and their electween the sounders and the stationary field memtrostatic pickfup and 13 is a fragmentary bers f the picbups. perspective vlew illustrating a pair of vibratile Another object of this invention is to provide bars and means for moving the electrostatic an instrument of the character mentioned empick'up to produce tremolo eflect' The instrument provided by the present inbodylng a novel deviceor attachment for rapidly moving the electrostatic pickups toward and ventlon may take various forms and may be var ied considerably to produce tones of various qual- 0 a from the vibratile Sounders Pmduce ities. In the following detailed disclosureI will Varlable r f effectdescribe several different forms and applications Ano r J t Of s ven 5 t0 Provide of the invention, it being understood that the an electrical musical instrument of the character nti n i not to b construed as limited or mentioned in which the vibratory sounding bars restricted to the specific forms or applications 5 are pp r ed by novel means at their n del about to be described.

Fig. 1 of the drawings illustrates a cabinet or case In of the character in which the parts and mechanisms of any one of the various forms of the invention may be housed in the event the instrument is to be under direct manual control and manipulation. The case l0 illustrated includes two lower side portions adapted to contain various mechanisms such as the loud speaker. the tremolo producing mechanism and the like. The space |2 occurring between the side portions l is adapted to receive the knees of the musician. A keyboard l3 extends horizontally across the upper forward The keyboard |3 may comprise a multiplicity of depressible keys |4 arrangement as the series of pull knobs board l3 for the control mentalities of the instrument. |6 and I1 is provided in the certain controls to be hereinafter described. It is to be understood that the case |0 illustrated in the drawings is merely typical in design and that the instrument may be housed in cases or cabinets of various designs and constructions.

The form or embodiment of the invention illustrated in Figs. 2 to '7, inclusive, of the drawings, includes, generally, a multiplicity of tuned vibrators or sounders 20, means 2| individually supporting the sounders 20 for independent vibration, means 22 for actuating or vibrating the sounders 20, electrostatic pick-ups 23 receptive to vibrations of the sounders fying and loud speaker circuit 24 for converting variations in the potentials of the pick-ups 23 into sound. The conductors in this circuit are preferably shielded by grounded shields as indicated diagrammatically at 24' at the left of the circuit in Figure'2.

The vibratile elements or sounders are adapted to be vibrated to vary the potentials of the fields of the pick-ups 23 and thus produce modulations in an electrical current which modulations are translated into'sound by the speaker circuit 24. In the particular form of the invention being described the sounders 20 are in the form of bifurcated metal bars or forks each having a pair of spaced tines 25. Each forkor sounder 20 has a shank 26 projecting longitudinally from the point of juncture of its tines25. The sounders although they are of different lengths and proortions to produce vibrations corresponding to or proportional to the vibrations of various tones. In practice the sounders 20 are graduated in length and are formed and tuned to be capable of producing a full scale or at least a musical scale of substantial range. The tines 25 of each sounder are preferably substantially parallel. The sounders 20 are preferably, though not necessarily, formed of steel or other electrical conducting material. The shanks 26 of the soundkeys of a piano or organ. A I5 is provided above the keyof certain instru- A pair of pedals ers 20 are comparatively heavy or thick to be subject to a minimum of vibration. The shanks 26 of the several sounders 20 may be of substantially the same length.

The means 2| sounders 20 supports the sounders for independent vibration and in an orderly and compact relation. The means 2| includes a suitable carrier 21. The carrier 21 is an elongate member of substantially L-shaped transverse cross section having a longitudinal flange 28 projecting upwardly along one edge. Where the instrument is housed in a case similar to the case face'of the case Ill.

of the same character and space l2 to govern posing surfaces of the flange 20 and an ampli- 20 may be similar in shape and construction -25 are in alignment mounting or supporting the Hi the carrier 21 is preferably arranged in a horizontal position in the main upper portion or the case. A covering or layer 29 of vibration dampening and acoustical insulating material is provided on the upper surface of the carrier 21 and the inner side of its flange 28. The means 2| further includes blocks 30 for independently or individually supporting the sounders 20. There is a block 30 provided for carrying each sounder 20. The blocks 30 are formed of wood or the equivalent. In accordance with the invention the blocks- 30 are supported on the layer 29. of acoustical insulation and each block 30 has a flange 3| at one end bearing against the flange 28 through the medium of the insulation layer 29.

A plate 32 extends along the upper edge of the flange. 28 and has a lip 33 extending downwardly at the inner side of the flange 3|. Acoustical insulating material 34 is interposed between the plate 32 and the lip 33 of the plate and the op- 3|. An anchoring plate35 may be suitably secured to the outer or plain end portion of each block'30 and an angle iron 36 may extend along the plain end of the carrier 31 to engage downwardly against the plates 35. Acoustical insulation 31 is nterposed between the opposing surfaces of the plates 35 and the angle. iron 36, The plate 32 and the angle iron 36 secure the several blocks 30 against excessive movement and displacement. In accordance with the invention the blocks 30 are insulated from one block to the other. Spaced buttons 38 are provided between and space the opposing surfaces of the blocks 30 and their flanges 3|. The buttons 38 are formed of vibration absorbing and acoustical insulating material. The plurality of blocks 30 may be of the same length to have their plain or .unflanged ends in alignment. In practice the plain end or edge portion of the carrier 21 projects beyond the adjacent ends of the blocks 30.

In accordance with the invention an upwardly facing shoulder or seat 39 is provided on each block 30. The seats 39 occur adjacent the flanges 3| and are elevated above the principal upper surfaces of the blocks. The spacing of the seats 39 from the outer or plain ends of the blocks 30 is graduated in directproportiontothe lengths of the graduated tuned sounders 20. The shanks ZBof'the sounders 20 rest on the seats 39. Screws 40 or the like, may secure the shanks 26 to the seats 39. The seats 39 support the soundders 20 so that their tines25 are spaced one above the other with the lower tines 25 spaced a sufiicient distance above the blocks 30 so that they cannot contact the blocks when vibrating.

The sounders 20 are supported on the graduated seats 39 so that the outer ends of their tines adjacent the outer ends of The sounders 2|! individually the blocks 30.

mounted as just described may vibratewith a minimum of vibratile interference.

The means 22 for vibrating the sounders 20 may be varied in character without departing from the broader aspects of the invention. In the particular case'illustratedthe means 22 for actuating the sounders 20 includes the keys M of the key-board '|3. The keys M have their inner ends pivotally supported on a suitable horizontal support 4|. Pivot pins 42 project from the support 4| into lined openings 43 in the inner portions of the keys l4. connected with the inner ends of the keys l4 Springs 44 are IJI'LOII.

to return the keys and to normally retain them in their horizontal positions. A horisontal support 45 is spaced below the forward end portions of the keys l4. Guide pins 4|v proiect from the support 45 and extend into lin'ed openings 41 in the keys l4. Brackets or hangers 48 depend from the support 45 and pivot pins 49 pivotally secure hammers 58 to the hangers 48. The hammers 50 have heads of feltvor the like for striking against the upper tines 25 of the sounders 20. It is to be understood that there is one key l4 and one hammer 5|] for each Springs 54 are connected with the hammers 56' and normally hold them in their retracted positions against felt stops 55.

A pivotally supported lever 56 is provided below each hammer 58. The levers 56 carry felt pads 51 for contacting the upper tines 25 of the sounders 28 to dampen the vibration of the sounders. Springs 58 act on the levers 56 to hold their felts or pads 51 against the tines 25. Push rods 59 are engageable by the keys 4 when the keys are depressed to pivot the levers 56 and move their felt pads 51 out of contact with the tines 25 so that the sounders 28 may be free to vibrate. A control bar 68 extends horizontally above the outer arms of the levers 56. A link 6| operatively connects the pedal S with the bar 60. When the pedal 6 is depressed the bar 60 is moved downwardly to pivot the several levers 56 to positions where their felt pads 51 are clear of the tines 25. Thus depression of the pedal l6 operates to sustain the tones produced by vibration of the sounders 20. It is obvious that various changes may be made in the mechanism just described, for actuating the sounders 20,

without departing from the invention.

The electrostatic pick-,ups 23 are operable to convert vibrations of the sounders 20 into modulations in the potential of an electrical current which modulations are in turn translated into sound by the amplifying and loud speaker circuit 24. In accordance with the invention 11 separate or individual pick-up 23 is provided for each vibratile sounder 28. The pick-ups 23 may be simple integral members of suitable electrical conducting non-magnetic material. In the preferred construction the pick-ups 23 are secured to the plain or outer ends of the blocks 30. The pick-ups 23 are preferably adjustably secured to the blocks 38 so that they may be adjusted relative to the tines 25 of the sounders 38. Each pick-up 23 is provided with a vertical slot 62 and screws 63 pass through the slots 62 and are threaded into the blocks 38 to secure the pick-ups to the blocks. Washers 64 may be provided under 1 the heads of the screws 63. When the screws 63 are loose or loosened the pick-ups 23 may be adjusted vertically. The screws 63 may be tightened down to rigidly secure the pick-ups 23 in their adjusted positions.

Each pick-up 23 has a laterally or horizontally projecting arm 23 The arms 23 are positioned above and are substantially parallel with the lower tines 25 of the sounders 20. The arms 23 are located so that they are not contacted by the tines when the sounders 28 are vibrated. Being located above the lower tines N' there is little orno dancer 0! the arms Il being contacted by the tines when the sounders are struck by the hammers 80. The invention, however, preferably provides a pad 86 of felt, or the like, on each pick-up arm 23- above the outer extremity of the adjacent lower tine 25 to positively prevent the tine from contacting the pick-up arm in the event the sounder is excessively vibrated.

In the preferred construction the lower tines 25 of the pick-ups 23 constitute the movable elements or armatures of the pick-ups. A common conductor or bus rod 66 is provided above or adjacent the shanks 26 of the series of sounders 20 and leads 6'! electrically connect the individual sounders 20 with the bus rod 66. A common conductor or busrod 68 extends horizontally adjacent the series of pick-ups 23 and leads 69 electrically connect the individual pick-ups with the rod 68. In accordance with the invention the assembly of vthe series of sounders 28 and their pick-ups 23 is shielded against external movements and disturbances. A shield of magnetic iron or soft iron extends around the carrier 21 and has its upper portion extending over the major portion of the assembly. The shield 18 preferably has a web 1| extending horizontally between the upper and lower tines 25 of the sounders 28. The shield '10 thus encloses or substantially encloses the sounders 20, the pick-ups 23, the rods 66 and 68 and the leads 6'! and 69. The upper tines 25 of the sounders 28 project outwardly above the shield web 1| to be engageable by the hammers 50 and the dampening pads 51.

The amplifying and loud speaker unit or circuit 24 is subject to variations in the potentials in the electrostatic pick-ups 23 produced by vibrations of the sounders 20 and translates or converts the fluctuations or variations into sound. In accordance with the broader aspects of the invention the unit or circuit 24 may be varied considerably in character. The particular system or circuit 24 illustrated includes an amplifying circuit 13 supplied with electrical current through the medium of a suitable transformer 14.

Leads electrically connect the bus rods 68 and 66 with the amplifying circuit 13. Electrical conductors 16 extend from the transformer 14 to a suitable loud speaker Tl. The invention provides a secondary circuit 18 supplied with current by lines I9 through a transformer 80. The circuit 18 is electrically connected with the speaker unit or speaker 11. A variable rheostat 8| is interposed in one lead I8 of the circuit 18. The movable element of the rheostat 8| may be controlled or moved by the pedal IT as diagrammatically illustrated in Fig. 2 of the drawings. The rheostat 8| is adapted to govern the intensity or volume of the sound produced by the speaker 11. It will be apparent how variations in thepotentials of the pick-ups 23 produced by vibrations of the sounders are transmitted to the speaker 11 through the amplifying circuit 13 to be produced as sound or musical tones. The musician may control the volume of the sound thus produced by manipulation or control of the pedal I1.

The invention may include a means for producing a tremolo effect in the sound or musical tones produced by the speaker 11. The tremolo producing means may include a base 82 provided with a pair of upstanding standards 83. A shaft 84 is rotatably supported by bearings 85 on the standards 83. The tremolo producing means is point.

in the nature of a variable condenser and includes a rotor 88 fixed on the shaft 84 and a relatively stationary stator 81. The rotor 88 and the stator 81 are in the form of semi-discs or partial discs. A foot flange 88 is secured to the stator 81 and may rest on-the base 82; provided in the flange 88 andpins or screws 98 extend through the slot 89 into the base 82. The flange 88 carrying the shiftable on the base 82 and the pins 98 serve to guide the fiangeand prevent it from lifting from the base. The stator 81 is adapted to be manually shifted or controlled from a remote A lever 92 is suitably pivotally mounted on one of the standards 83 and is connected with the flange 88 by a suitable link 93. may be pivoted by manipulation of one of the pull knobs I5 through a suitable control mechanism to effect shifting of the stator 81 axially relative to the rotor 88. a

The rotor 86 is intended to be rotated at a constant speed to produce the tremolo effect. In the typical arrangement illustrated a driven shaft 84 driven by a suitable power means (not shown) is arranged in spaced parallel relation with the' shaft 84. A belt and pulley drive 95 operatlvely connects the shaft 94 with the shaft 84.-The power means driving the shaft 94 may be controlled -or energized by the musician so that the tremolo producing means may be employed at his option. It will be apparent how constant rotation of the partially disc shaped rotor 88 rela tive to the partially disc shaped stator 81 effects a regular surge or variation in the potential of the circuit to produce a tremolo effect on the tones emitted by the speaker 11. The'intensity ofthis tremolo effect may be readily governed by shifting the stator 81 relative to the rotor 86.

In the operation of the instrument the musician may depress or manipulate the keys I4 in the same manner as the keys of an organ or piano. Depression of the keys causes their respective hammers 58 to strike the aligned upper sounder tines 25 to vibrate the sounders. "The vibrating lower tines 25 of the sounders 28 vary the electrical potentials of the fields at the pickups 23 to produce variations or modulations in the electrical circuit in which the pick-ups are connected. These fluctuations or variations are amplified by the circuit I3 and'are translated into sound by the speaker 11. The sound produced by the speaker I1 is thus truly representative of the physical vibrations of the sounders The sounders 28 are mounted or supported by the means 2I for independent vibration so that the vibration of one sounder does not produce sympathetic vibrations of the adjacent sounders. Accordingly, there is little or no interference of vibration to the sounders. The instrument embodies several controls whereby the intensity, duration and character of the tones may be readily governed by the musician. The pedal It may be manipulated to control the time or periods the tones are sustained. The pedal I1 may be manipulated to readily govern the intensity of the tones produced by the speaker 11. The tremolo producing device may be employed at the option of the musician. When it is desired to produce tremulous tones the motor or power means driving the shaft 94 is energized to effect constant rotation of the rotor 88 and one of the pull buttons I5 may be shifted as desired, to control the intensity of the tremolo effect. The instrument is capable of producing clear pleasing An elongate slot 89 is stator 81 is adjustable or- The lever 92 musical tones and may be easily played and manipulated by the musician.

Fig. '7 of the drawings illustrates-a group of sounders 28 in the form of bars of rectangular transverse cross section. The sounders 28 are formed of steel or the like and are prefer'ablyarranged horizontally and in parallelism. In accordance with the invention the sounders 28 are formed and proportioned to produce vibrations of various frequencies and thus produce various musical-tones and the group of sounders 28' may be capable of producing a complete musical scale. A carrier 21 is provided to support the sounders 28*. The carrier 2l is an elongate trough-like structure having parallel flanges 28 projecting upwardly along its longitudinal edges. Two

spaced strips 98 are arranged on the upper surface of the carrier 2'! between its flanges 28 The upper edges of the strips 98 are bevelled to relatively sharp ridges. The bars or sounders 28 are supported at their nodal points on the ridges the strips 96 to cooperate with openings in the bars or sounders 28 to hold the sounders in place.

An electrostatic pick-up 23 is provided for each bar sounder 28 The pick-ups 23 may comprise blocks or members of. electrical conducting non-magnetic material. The pickw-ups 28% are preferablysupported on the carrier 21*. In the arrangement illustrated the pick ups l3 are each supported one. block 98 which {in turn rests on the upper surface of 'the fcarrie'r- 21'. -The pick-' ups 23 are located (substantially midway between the nodes of the soundersso that there is no physical contact between the sounders and pickups when the sounders are invibration. A common lead or conductor 99 is electrically connected with the several pick-ups 23. The metal or steel sounders 28 preferably comprise the movable armatures of the electrostatic pick-ups 23*. A common lead or conductor I88 is electrically connected with each of the several sounders 28, being connected with each sounder at or strips 98. Pins 91 may be provided on Plates I83 preferably extend along the upper edges of the bed IM and have flanges I84 extending downwardly at the inner sides of the flanges 28 to hold thecarrier 21- in place. Acoustical insulation I85 is interposed between the surfaces of the flanges 28 and the plates I83 and theirilanges I84.

The assembly illustrated in Fig. 7 of the drawings may be embodied in the musical instrument in substitution for the sounders 28 described above, or may be embodied in the instrument with suitable actuating hammers in addition to the sounders as shown whereby the instrument is adapted to produce musical tones of a different quality. It will be apparent how the assembly illustrated in Fig. 7 may be readily arranged in V a cabinet similar to the cabinet or case I 8 to have its sounders 28 actuated by key controlled hammers.

Fig. 8 of the drawings illustrates a bar type sounder 28 formed of wood. The sounder 28 is an elongate member preferably of rectangular cross section. The lower side of the sounder 20 is preferably flat while the upper side of the sounder is transversely grooved or provided with a depression I08 at a point midway between its nodes. The depression I08 is provided to tune the sounder and to give the sounder the desired quality of tone. A suitably insulated base I09 is provided to support the sounder-20 Two spaced strips or posts Il project upwardly from the base I051. The upper ends of the posts IIO are bevelled to present relatively sharp ridges. The bar sounder 20 is supported at its nodal points on the ridges of the posts I I0 to be free to vibrate in its characteristic manner. Pins or screws III pass through openings H2 in the sounder 20 and are threaded into the posts IIO to retain the sounder in position. Acoustical insulating material II3 lines the openings H2 and is provided under the heads of the screws III to prevent direct physical contact between the sounder 20 and the screws. I

An electrostatic pick-up 23 is provided for the sounder 20. The pick-up 23 is in the nature of a disc oi" electrical conducting non-magnetic material. The pick-up 23 is supported on the upper end of a post I I4 which rests on the base 109 through a washer II5 of insulating material. The disc pick-up 23 is arranged in horizontal position and is spaced below the sounder 23 The pick-up 23 is located substantially mid-way between the nodal points of the sounder 20 The pick-up 23 further includes an armature H6 on the underside of the sounder 20 The armature I I6 is preferably in the nature of a piece of foil of electrical conducting non-magnetic material. The armature I I6 is secured to the flat under side of the sounder 20 to be immediately above the disc pick-up 23 An electrical lead II? is connected with the armature H6 and ex tends along the under surface of the sounder 20 to one of its nodal points. The conductor H1 may extend freely from one of the posts III] to be directed to the desired point. A lead or conductor H8 is connected with the disc pick-up 23 The leads II! and H8 are adapted to be connected in a suitable amplifying and loud speaker circuit.

The musical instrument of the .present invention is adapted to be provided with a multiplicity of sounders 20 of different or graduated pitch, which sounders may be actuated or vibrated by suitable key controlled hammers similar to the hammers 50. The group of sounders 20 may be substituted for the sounders 20 or 20. When a sounder 20 20 or 20 is vibrated by means of a hammer or the like the armature II6 on its under side moves or vibrates relative to the stationary disc pick-up 23 to produce variations in the potential of the pick-up field. Thus the electrical circuit in which the pick-up is connected is subjected to fluctuations or variations which are imposed on the amplifying and loud speaker circuit to be translated into sound. The wooden sounders 20 of course produce tones of a different character andv quality than the metallic sounders 20 and 20.

Figs. 9 and 10 of the drawings illustrate an improved manner of mounting a bar type sounder similar in character to the sounder 20 Transverse openings I20 are provided in the sounder 20 exactly at its nodal points. A pivot I pin I2I preferably of catgut, or the like, is passed through each opening I20 to have its opposite end portions project from the sides of the sounder. A cradle I22 is positioned below each nodal point of the sounder 20 and has two upstanding arms I23. The arms I23 project upwardly at the opposite longitudinal edges of the sounder 20 and their upper portions are slit or bifurcated. A transverse opening I24 is provided in each arm 23 in the plane of and in communication with its slit or bifurcation. The openings I24 receive the projecting portions of the pivot pins I2I. Screws I25 are provided to clamp the slit portions of the arms I23 together to retain the pivot pins I2I in the openings I24. The sounder 20 supported in the manner just described is free to vibrate at will in its characteristic manner to produce sustained vibrations of a peculiar character. It is to be understood that the sounder 20 may be provided with an armature II6 to be associated with a pick-up 23 in the manner described above. 20 and the sounders illustrated in Figs. 11 and 12 of the drawings may be mounted in any suitable manner.

Fig. 11 illustrates a sounder 20 of the general character illustrated in Figs. 8, 9 and 10. The bar sounder 20 may be employed or utilized in the same manner as the sounders 20 and 20. The sounder 20 may be provided with a transverse groove or depression I08 between its nodal points. In accordance with the invention one or more elongate slits I26 are provided in the sounder 20 The slits I26 extend longitudinally of the sounder and occur' in the portion of the sounder between the nodal points. The slits I26 thus occur in the portion of the sounder made thin by the presence of the depression I08. The slits I26 divide the sounder into three integrally connected portions, one being adapted to produce fundamental tone vibrations, and the other two portions being adapted to produce partials or harmonics of said fundamental. The slotting of the bar tends to allow more freedom of vibration where the slots occur at the middle of the bar. The provision of slots of different lengths tends to cause the bar to vibrate at more than one periodicity due to its breaking into a natural movement over each section on account of its elasticity. This causes a harmonic movement superimposed upon the fundamental movement such as happens in the vibration of a piano string and results in a composite tone. The slots or slits I26 are proportioned to give the bar or sounder 20 the desired pitch and the desired quality of tone. The type of sounder illustrated in Fig. 11 of the drawings may be associated with an electrostatic pick-up in the same manner as the sounders 20 and 20 and may be mounted for vibration in any suitable manner. sounder 20 is vibrated it produces compound tone.

Fig. 12 of the drawings illustrates a plurality of adjacent bar sounders 20 adapted to be vibrated simultaneously to produce a compound tone. In the arrangement shown the total width of the three bars 20 in one group is intended to be substantially the same as the width of one of the bars or forks 20 or 25 so that a hammer such as 5I will strike all of the bars in the set simultaneously. This is similar to the manner in which the hammer of a piano strikes the three strings of a middle register simultaneously. In the particular arrangement illustrated there are three toned vibratile bar sounders 20 graduated in length. The longest sounder 20 may be considered the fundamental sounder capable of vi-.

The sounder When the a pleasing 15 Upon simultaneous vibration of a 25 a tremolo effect.

60 bracket I44. A cam 10 sounders 20 substantially midway between their nodes. Individual movable armatures similar to the armature II6 described above are provided on the under sides of the sounders 20 to be directly above and spaced from the pick-up 23. group of sounders 20 the potential of 'the pick-up field is varied and the resultant modulations in the electrical current may be converted into sound by a suitable amplifying .and loud speaker circuit. It

20 will be apparent that the instrument may be provided with a series of groups, of sounders 20 to be vibrated by key controlled hammers to produce compound tones.

Fig. 13 illustrates another means for producing In the structure illustrated in .Fig. 13 two bar sounders 20 are supported at their nodes by suitable supports I40. The sup ports I40are carried by a base I4I spaced below the sounders. 20f. The sounders 20f may be-steel 30 bars of different diameters whereby they are capable of producing vibrations of different frequencies. The sounders 20f may be vibrated simultaneously orindividually by means of hammers similar to. the hammers 50 described above.

35 It is to be understood that there may be any desired number of sounders 20].

An electrostatic pick up 23a is provided for the sounders 201. The pick-up 23d may comprise a member of electrical conducting non-magnetic 40 material arranged'transversely below the sounders 20 f at their points of maximum vibration. In accordance with the inventionthe electrostatic pick-up 2301 is supported for movement relative to the vibratile bar sounders 20f. A member I42 45 is pivotally supported on the baseI4I below the sounders 20f. A block I43 is arranged on the member I42 and carries the electrostatic pick-up 23d. 2

Means is provided to regularly oscillate or .move the pivoted member I42 to constantly change the position of the electrostatic pick-up 23d relative to the sounders 20f. A suitable bracket I44 is located above the assembly of sounders 20 f. -A substantially vertical rod I45 is v 55 guided for vertical movement by the bracket I44 and has its lower end pivotally connected with the member I42. An arm I46 is fixed to and projects, from the rod I45. A transverse or horirotatably supported by the,

zontal shaft I41 is I48 is fixed to the shaft I41 and cooperates with the arm I46 to move the rod I45 vertically. A pulley I49 is fixed on theshaft I41 and a driven belt I50 operates over the pulley I49 to rotate the shaft I41. The shaft I41 5- is preferably rotated at a constant speed. A

spring Ill is preferably associated with the shaft I4! to urle its arm I40 against the cam I40 and to positively return the rod and the member I42 to their lower positions. A common lead or conductor I52 is connected with the several sounders 201. A similar conductor I53 is connected with the electrostatic pick-up 23d. The leads I52 and I53 are adapted to be connected in a suitable amplifying and loud speaker circuit.

In the operation of the apparatus illustrated in Fig. 13 of the drawings the shaft I41 may be constantly rotated by the belt I50 so that the pick-up 23d. is moved toward and away from the bar sounders 20f at a relatively rapid rate. When a sounder 20! is vibrated its vibration varies the potential in the electric field of the pick-up 23d to produce modulations or fluctuations in the electrical current of the pick-up circuit, which fluctuations may be translated into soundby the amplifying and loud speaker circuit. The driven cam I48 effects continuous reciprocation of the rod I45 to move the pick-up 23d. toward and away from the sounders 201.

Accordingly, the intensity of the variations in the potential of the pick-up field is constantly varied and the tones produced by the loud speaker aretremulous. It is to be understood that the belt I50 need not be continuously driven but may be driven at the option of the musician. When the cam I48 is idle the pick-up 23d is stationary relative tothe sounders 20 so that no tremolo effect is produced. The tremolo producing means illustrated in Fig. 13 of the drawings may be employed in conjunction with other forms of the invention.

Having described only typical preferred forms and applications of my invention, I do not wish to be limited or restricted to the specific details herein set forth, but wish to reserve to myself any variations or modifications that may appear to those skilled in the art or fall within the scope of the following claims.

Having described my invention, I claim:

1. In an electrical musical instrument, a vibratile sounder, an electrostatic pick-up coacting withsaid sounder, means supporting the pick-up for movement toward and away from the sounder, andpower driven cam means for moving the pick-unto produce a tremolo effect.

2. In an electric musical instrument, the combination of a metallic shield, va support mounted in -the shield, a plurality of blocks carried by the support, means for insulating said blocks one from another, a vibrating fork mounted on each block, manually operable means for vibrating therespective forks, an electrostatic pick-up mounted on each block to coact with the fork on said block, a bus bar, electrical connections from said bus bar to each fork, a second bus bar, electrical connections from said second-named bus bar to each pick-up, said bus bars being connected with sound translating means, including a loud speaker, as and for the purposes described.

VICTOR H. SEVERY. 

